OLE/COM objects report errors through the HRESULT return code of object member functions. An OLE/COM HRESULT is a bit-packed structure. OLE provides macros that dereference structure members.
OLE/COM specifies the IErrorInfo interface. The interface exposes methods such as GetDescription, allowing clients to extract error detail from OLE/COM servers. OLE DB extends IErrorInfo to support the return of multiple error information packets on a single-member function execution.
SQLOLEDB exposes the OLE DB record-enhanced IErrorInfo, the custom ISQLErrorInfo, and the provider-specific ISQLServerErrorInfo error object interfaces.